//
// "$Id: fl_overlay_visual.cxx 8864 2011-07-19 04:49:30Z greg.ercolano $"
//
// X overlay support for the Fast Light Tool Kit (FLTK).
//
// Copyright 1998-2010 by Bill Spitzak and others.
//
// This library is free software. Distribution and use rights are outlined in
// the file "COPYING" which should have been included with this file.  If this
// file is missing or damaged, see the license at:
//
//     http://www.fltk.org/COPYING.php
//
// Please report all bugs and problems on the following page:
//
//     http://www.fltk.org/str.php
//

// Return an overlay visual, if any.  Also allocate a colormap and
// record the depth for fl_color() to use.
// Another disgusting X interface, based on code extracted and
// purified with great difficulty from XLayerUtil.cxx:

#include "fltk_config.h"
#if HAVE_OVERLAY
#include "Fl.H"
#include "x.H"

// SERVER_OVERLAY_VISUALS property element:
struct OverlayInfo {
	long overlay_visual;
	long transparent_type;
	long value;
	long layer;
};

extern Colormap fl_overlay_colormap;
extern XVisualInfo* fl_overlay_visual;
extern ulong fl_transparent_pixel;

XVisualInfo *fl_find_overlay_visual()
{
	static char beenhere;
	if (beenhere) return fl_overlay_visual;
	beenhere = 1;

	fl_open_display();
	Atom overlayVisualsAtom =
	        XInternAtom(fl_display,"SERVER_OVERLAY_VISUALS",1);
	if (!overlayVisualsAtom) return 0;
	OverlayInfo *overlayInfo;
	ulong sizeData, bytesLeft;
	Atom actualType;
	int actualFormat;
	if (XGetWindowProperty(fl_display, RootWindow(fl_display, fl_screen),
	                       overlayVisualsAtom, 0L, 10000L, False,
	                       overlayVisualsAtom, &actualType, &actualFormat,
	                       &sizeData, &bytesLeft,
	                       (unsigned char **) &overlayInfo)) return 0;

	if (actualType == overlayVisualsAtom && actualFormat == 32) {
		int n = int(sizeData/4);
		XVisualInfo* v = 0;
		// find the greatest depth that has a transparent pixel:
		for (int i = 0; i < n; i++) {
			if (overlayInfo[i].transparent_type != 1) continue;
			if (overlayInfo[i].layer <= 0) continue;
			XVisualInfo templt;
			templt.visualid = overlayInfo[i].overlay_visual;
			int num;
			XVisualInfo *v1=XGetVisualInfo(fl_display, VisualIDMask, &templt, &num);
			if (v1->screen == fl_screen && v1->c_class == PseudoColor
			    && (!v || v1->depth > v->depth && v1->depth <= 8)) {
				if (v) XFree((char*)v);
				v = v1;
				fl_transparent_pixel = overlayInfo[i].value;
			} else {
				XFree((char*)v1);
			}
		}
		if (v) {
			fl_overlay_visual = v;
			fl_overlay_colormap =
			        XCreateColormap(fl_display, RootWindow(fl_display, fl_screen),
			                        v->visual, AllocNone);
		}
	}
	XFree((char*)overlayInfo);
	//printf("overlay visual %ld selected\n", fl_overlay_visual->visualid);
	return fl_overlay_visual;
}

#endif

//
// End of "$Id: fl_overlay_visual.cxx 8864 2011-07-19 04:49:30Z greg.ercolano $".
//
